try this it fixed my genral protection faults and auto reboots buring gameplay.
boot into your bios !
find a setting (may be diffrently spelled on your mobo)
Apg Voltage :
change it to 1.7v if that will not work change it to 1.8v
nothing will happen all its doing is giveing yoru grafix card more juce to play with.
Unreal 2 is a very very intence game on your hardware.
give it a shot it may work for you . if not at 1.7 then try 1.8 if not at 1.8 then its not whats causeing the problem.